Electrocardiograph



March 12, 1940. E} T, BOTH -2 ,193,471

ELECTfiOCARDIOGRABX-l Filed Oct. 2, 1957 s Sheets-Sheet 1 'n wl mnwlmeINVENTOR= EDWARD THOMAS BOTH BY r " ATroRmix s March 12, 1940. E. T.BEOTH Y 2,193,471

ELEGTROCARDIOGRAPH Filed Oct. 2, 1957 s Shets-Sheet 2 |NVENTOR= EDWARDTHOMAS BOTH ATTOR N EYJ,

7 March 12,1940. -E,T BOTH 2,193,471

- I ELECTROCARDIOGRAPH ,rFiled Oct. 2, 19:57- 5 Shets-Sheet s I 3 IN vEDWARD THO R1 I Q MAS BOTH jwwmvzk AT'TORNEYS to amplify the actioncurrent of a heart, and to- Patented Mar. 12,1940

Edward Thomas Both, Adelaide,

South Australia,

Australia, assignor to Both Eleetro Uardiograph Limited, Adelaide,Australia, ,a company of Australia Application October a, 1937, SerialNo. 166,919

8 Claims. (01. 1ze 2.os)

This invention relates to an improved electrocardiograph for use inrecording the action current of the heart by takingcross readings suchas between the right arm and left arm, the right arm and left leg. andbetween theleft arm and left leg, the principal object of the inventionbeing to provide recording means by which alinear record is made whichcan be viewed while it is being made and which remains readily availablethereafter, further objects being a construction by meansof whichsimplicity and ruggedness together with sensitivity and standardisationare-attained. e

According to this invention the recording means comprise a removablecardiogram disc 'of transparent material having on one side an opaquecoating which may be easily removed, a

narrow line of which coating is in operationremoved by a fine-pointedscriber which forms a trace by cutting through the coating, means beingprovided to support and revolve the disc,

convert such amplified action current-to mescriber. Y

The features of the invention will however ,be better understood ifreference is had to the following description which will be made withreference to the accompanying drawings in which- Fig. 1 is a sectionalside elevation showing an' embodimentof the improvedcardiograph arrangedinits case,

Fig. 2 is a diagram of the electrical circuit,

.-F'ig. 3 is a sectionalperspective view of the mechanism, Fig. 4 is asectional plan of same,

Fig. 5 is a sectional perspective view of the scriber supporting meansshowing the moving coil and the cardiogram-disc and turntable, and

' Fig. 6 is an enlarged view of the grating which is placed in themicroscope upon the usual platform provided in the eyepieces ofmicroscopes.

The-trace is made toa small scale on a transparent cardiogram disc Iwhich has its underside treated with a material which renders suchunderside opaque but which can be easily removed :by a scriber incontact with such disc. A suitable method of rendering the disc opaqueis to deposit carbon by smoking such disc. The term chanical movementwhich is applied to the "opaque" is intended to include a semi-opaquestate ash is not always necessary to have the coating-completely opaque.

The disc is supported upon a turntable 2 which is of smaller diameterthan the cardiogram disc table 2 against such shaft 4.

I and this turntable 2 is slowly driven by means of a spring motor 3 byextending the shaft 4' of the spring casing 5 which is. attached to thegear wheel -6 and bringing the edge of the tum- The turntable issupported by a bearing member I mounted upon the end of a spring arm 8projecting from a block 9 secured upon the motor 3. A ball-bearing Illis interposed between the dis and the member,

I and the disc is steadied by resting it upon a H post H projectingupwardly from a frame l2 which also supports the motor 3. The member 1beers upon a plate I1 secured to the motor.

The spring/arm 8 forces the turntable 2 against the 'shaft 4 and theturntable is thus given a very steady rotation at a low rate ofrevolution. The motor 3 can be of any usual or approved constructionprovided the gear wheel 6 of the spring-can be-coupled to the shaft- 4to revolve samau The spring motor has the usual governor l3 and speedregulating'means l4 these latter being adjusted by a screw I 5.

The location of the'disc I upon the top of the turntable 2, and thelocation of the scriber-to operate upon the coated underside of thedisc,

ensures that the space above the turntable is clear of mechanism andeasy positioning and removal of the disc results, the danger of damagingthe delicate scriber during positioning and removal of the disc beingremoved, and mounting of the scriber being made'.more practical.

The disc I (of which a number are provided) has-at its centre a knob l6which has a downwardly-projecting centering portion.

The unit for converting the amplified current variation to mechanicalmotion is a moving-coil unit '20 comprising a permanent magnet 2|, and

a moving coil 22 the coil former 23 of which is supported on flexiblearms 24 in any usual or approved manner to permit free axial movement.Secured to the coil former 23 is an arm 25 which projects in thedirection of axial movement of the coil, the 'arm having on itsprojecting end an upwardly-projecting scriber 26 in the top of which isa diamond point, The arm 25 is constructed to be rigid excepting at-'2'|at which point it can flex to allow the scriber 26 to move up and down.This arm transmits to the scriliier 26 the axial movement of the movingcoil 22 due to current variation and when'such scriber is in contactwith the revolving cardiogram' disc I such axial movement is faithfullyrecorded on the disc.

It will be realised that other suitable converters I could be used inplace ofthe moving-coil unit from moving down too far.

provided one is chosen which has a sufficiently quick response.

It is, however, very necessary tosupport the' er 26 and at its other endto abracket projecting from the magnet 2|. The arm 29 must be rigid in adirection to withstand any tendency to tilt of the scriber 26 due tofriction between the scriber and the rotating disc but must at the sametime be flexible so as not to resist the axial movement of 'the coilformer 23. This is achieved by having the arm 29 in the form of aflexible blade having the portion near the scriber 26 set upright buthaving the portion near the bracket 30 twisted at right-angles thereto.

From the foregoing it will be realised that the scriber 26 is heldagainst tilting by the arms 25 and 29 but is free to move up and downand to move axially under influence of the moving coil unit 20. The arms25 and 29 are so arranged that the scriber 26 is projected lightlyagainst the cardiogram disc when a trace is being made, but the scribermay be manually retracted from the disc by means of an arm 32 mountedupon a rockable shaft 33 when a trace is not being made. a

It is sometimes desirable to damp the scriber 26 against a too free upand down movement and this is achieved by securing a spring bracket 34to the coil former 23 immediately adjacent the arm 25, the end of suchspring bracket having an upwardly-projecting damper 35 which bearslightly against the arm 25. The spring bracket 34, as will be seen,consists of a flat strip arranged on edge so that it can flex to pressthe damper 35 against the arm 25 butwill not allow vertical movement ofthe damper 35. A small lug 36 upon the bracket 34 prevents the arm 25The aforesaid shaft 33 has attached to it an arm 40 which has its endcoupled to the end of an arm 4| which is rigidly secured to the lowerend of a vertical rod 42 slidable in a support 43.

The rod 42 is provided with a knob 44 and when this is pulled upwardlythe arm 4| is moved upwards, thus moving the end of the arm 40 upwardand rocking the shaft 33 with the member 32 and thus allowing thescriber 26 to rise and contact with the cardiogram disc I.

The rocking of the shaft 33 atthe same allows the motor 3 to start, thisbeing achieved by an arm 45 upon the end of the shaft 33 engaging theusual brake control 46 of the motor. It will thus be seen that upwardmovement of the knob 44 allows the motor to start and simultaneouslybrings the scriber 26 into contact with the cardiogram disc I and thatdownward movement. stops the motor and simultaneously moves the scriberaway from the disc. 1

As it is desirable to record a plurality of traceson each cardiogramdisc I, such as traces taken between the left arm and left leg, rightarm and left leg, and left arm and right arm and sometimes one furthertrace, switching means are provided to enable this to be done.

This is achieved by shifting the scriber 26 to different positions, theentire moving-coil unit 26 and the parts carried by it beingshifted. Forthis purpose the magnet 2| has upon it stems 56., 5| and 52 of which 56and 5|- areslidable in a bracket 53, and 52 is slidable in a bracket 54.The

direction of the stems is one to give axial movetime.

ment to the unit 20. Movement of the unit 26 is effected by means of acam 55 contacting with the back of the magnet 2|, such cam being mountedupon a shaft 56 provided with a control knob 51 and having at its bottomswitching means 56 which automatically change the leads from thepatient. From this it follows that when the moving-coil unit 20 isshifted to any one of the said positions the corresponding leads fromthe patient are placed into the circuit. Springs 59 maintain the magnet2| in contact with the cam 55.

To allow the trace to be viewed while bein recorded a microscope 60 isprovided, such microscope being of any usual or approved constructionand being supported by having a stem 6| upon it engaging in a socket 62forming part of aframe 63, which is secured to the case 64 which housesthe cardiograph. A focussing knob 65 is provided for the microscope andthe microscope is loosely mounted so that it can be removed from thesocket 62 and stored in the lid 66 of the unit as is shown moreparticularly in Fig. 1. The microscope has within it a grating of radiallines 61 to indicate an exact time interval for both the outer traceinscribed on such disc and the other traces which are nearer the centreand has cross lines 69 to indicate the amplitude of deflection of thescriber.

A lamp 68, preferably opalescent, is mounted beneath the cardiogram discI and in line with the microscope 60. The microscope is so located thatthe trace can be viewed immediately it has been traced on the cardiogramdisc I by the scriber 26. The lamp is energised by a battery 10 througha switch 1|.

The motor 3, the moving-coil unit 26, the lamp 68 and switch 58 are allsupported upon the aforesaid frame l2 which is in turn supported upon abase I2 but is raised some'distance above the base 12 by means of legs13.

The amplifier may be of any usual or approved I construction and mayconveniently be as shown in Fig. 2 of the drawings,

In this the switch 58 which controls the input in synchronism with thescriber position has two arms 19 and 60 whicheach co-act with contacts,the arm 19 engaging contacts 6| and the arm an engaging contacts 82.connected with the leads LA, RA, and LL which lead respectively to theleft arm, right arm and left leg of the patient for three-positionreadings. It will be seen that in the position of the arms 19 Thecontacts are inter II and 66 shown the reading is taken between LA coand RA, in the next position between RA and. LL, in the next positionbetween LA and LL; and in the fourth position again between RA and 'LL.I

The duplication of the position RA and LL is to enable a fourth trace tobe made by say removing BA from the patients right arm and placing it.

on his chest. Any one of the positions may also be used for calibrationlater to be described.

It will be noted that the input from the switch 58 is across the gridand filament of the valve VI. in

The valves V2 and V3 are resistance coupled, large condensers C1 and C2of say two microfarads being used to ensure adequate response to the'lowfrequency impulses. Sensitivity control is by means of the voltagec'ontrol R which regu lates the screen voltage of VI and V2. I The re.sistance RI across the winding of the moving coil 22 of the coil unitdampsthe movement to to the grid of the output valve V8 by C while thebias for valves VI and V2 is provided by the left hand portion of B. Thelatter battery is housed in the casing 83. It will be seen that theswitch -'II has three positions, one to allow the apparatus to beswitched off, another to allow the lamp 88 to be energised independentlyof the amplifier as for viewing of. a trace after recording; and anotherto energise both the lamp 68 and the amplifier.

' The potentiometer P across the input to VI has a metal knob 85 whichis connected through a condenser C3 with the slider of suchpotentiometer. The purpose of this isto enable -alternating currentintroduced by the patient toIVI tobe cancelled by feeding in'altematingcurrent of opposite phase (byreason of the condenser C3) from anoperator knob 85.

The before-mentioned means for producing a calibration trace comprise acam 81 upon'a shaft 88 which formspart of the motor 3 and which revolvesat a suitable speed, such cam actuating who holds and adjusts thecontacts 89 which are interposed between two resistances R2 and R3, thisseriesarrangement being connected aeross the filament supply of theamplifier. The cam periodically closes the contacts and applies a smallvoltage to such contacts which is transferred through the switch 90(when the arm' thereof engages the contact When the arm of the SI) tothe grid of VI. switch 90 is in the position shownusuch switchshortcircuits the contacts,

The value of the resistances R2 and R3 and the sensitivity of theamplifier is preferably such that one millivolt appliedto VI results ina scriber deflection of .3 of a millimeter. The

speed of rotationof the disc is such that approximately .03 of an inchis inscribed for each second of time.

The batteries A and. l3 are supported upon,

bases 93 and 94 respectively which are placed upwardly into the case 64and are secured thereto. The base I2 with the'parts upon it is alsoplaced upwardly into the case 64 and is secured thereto. The knobs 96and 91 operate the switch 90 and the resistance R. The socket 98 allowsthe leads LA, RA,.and- LL from the patient to be plugged in to thecardiograph;

,In operation the leads LAJRA, and LL are attached to the left arm,right arm and left leg respectively of the patient.

The amplifier is then switched on by operating the switch II andpreferably a standardisation trace is made this being achieved by movingthe switch arm 90 on to the contact SI and then operating the resistanceR. 'to adjust the sensitivity of the valves VI and V2. to bring theamplitude of the recorded impulses to the correct dimensions. The motor3 must of cburse be i started to revolve the cardiogram disc *I- and theshaft 88 before the trace can be recorded.

The sensitivity having been adjusted the switch 90 is returned to theposition-shown in Fig. 2

and the switch 58 is operated to place two leads from the patient intothe amplifier-circuit.

The action current of the heart introduced to the amplifier will causeactuation of the moving coil 22 of the unit 20 and this movement will beinscribed on the disc by the scriber 28.

One such trace having been obtained the switch 58 is set to its nextposition to place other leads from the patient into the amplifier input,this movement of the switch at the same time locating the scriber in anew position upon the disc by reason of the shaft 56. a

A third reading is similarly taken and if desired also a fourth reading.The fourth reading is achieved by placing the lead RA on the chest.

The fourth position may also be used to record on the disc astandardization trace but as a rule cam upon the operating --this is notnecessary for when the amplifier has been adjusted the correct amplitudewill be maintained for all. traces.

During. this recording the operator by means of the microscope may watchthe recording ,of the actual beats of the heart so thata direct.

diagnosis can be made.

. The trace upon the disc can be photographically recorded uponsensitized paper enlarged to a size to give a standardised reading, orthe disc may be stored as the record and viewed from time to-time underthe microscope if re- -quired.

,Should, during the recording of the trace,"

alternating current interference be introduced from the patientradiated-to'him from an alternatingcurrent lighting supply or the liketo the amplifier the operator who will also have the current radiated tohim places his hand upon the metal knob 85 and adjusts the potentiometerto introduce to the amplifier a current in phase opposition to thatintroduced by the patient and of balancing magnitude. It will beappreciated that the operator and the patient will in practice bereasonably close together and therefore will both pick up radiationssuch as those referred to (if such radiations are present) the contactof the operators hand with the metal knob of the potentiometer P makingthe necessary electrical connection to the saidknob and thus to thecondenser C3.

What I claim is:

1. An improved electrocardiograph comprising; a removable cardiogramdisc of transparent material having on one side an opaque coating whichmay be easily removed, a turntable to support said disc, a motor todrive said turn table, electrical means to amplify the action current ofa heart, a moving-coil magnetic unit to change the electricalimpulsesfrom the amplifier to mechanical movement, an arm projecting from themoving coil of the said unit disposed parallel torthe axis of movement,of the coil, a scriber secured upon the projecting end --of such arm,and a second arm secured at one end to the scriber and at its other endto a bracket projecting from the magnet of the said unit the lastsaidarm being tangentially disposed (at the' point of contact of thescriber) to the trace being inscribed, both said arms being flexible-tonormallyproject the scriber against the said cardiogram disc. 1'5 I I 2.An improved electrocardiograph comprising; 'a removable cardiogram 'discof transparent ma terial having on one side an opaque coating which maybe easily removed, a turntable to support said disc, a motor to drivesaid turntable, electrical means to amplify the action current of aheart, a converting unit to change the electrical impulses to mechanicalmovement, a scriber having a hard very fine point and coupled to movewith a moving part of said converting unit and arranged to inscribe aminute trace upon the disc by cutting through the coating, means toshift the said converting unit in a direction parallel to the directionof movement of the scriber to enable suc'h scriber to inscribe a numberof traces upon the said cardiogram disc, and switching means coupled tooperate with the shifting of the said converting unit to place difierentleads from the patient into circuit with the electrical amplifier whenthe said converting unit is in difierent positions.

3. An improved electrocardiograph comprising:

.a removable cardiogram disc of transparent material having on one sidean opaque coating which may be easily removed,, a turntable to supportsaid disc, a motor to drive said turntable, electrical means to amplifythe action current of a heart, a moving-coil magnetic unit to convertthe electrical impulses from the amplifier to mechanical movement, anarm projecting from the mov-, ing coil of the said unit said arm beingdisposed parallel to the axis of movement of the coil, a scriber securedupon the projecting end of such arm, a second arm secured at one end tothe scriber and at its other end to a bracket projecting from the magnetof the said unit the last-said arm being tangentially disposed '(at thepoint of contact of thescribef) to the trace being inscribed, both saidarms being flexible to normally project the scriber against the saidcardiogram disc, means to stop and start the said motor, and meanscoupled to such, last-said means to move the said scriber away from thecardiogram disc when the motor is stopped.

4. An improved electrocardiographcomprising: a removable cardiogram discof transparent material having on its underside an opaque coating whichmay be easily removed, a horizontally-disposed turntable of smallerdiameter than the said disc to support said disc upon its top, a motorto drive said turntable, electrical means to amplify the action currentof a heart, a converting unit to change the electrical impulses tomechanical movement, a scriber having a hard very fine point coupled tomove with a moving part of the said converting unit and arranged toinscribe minute traces upon the disc on that partthereof which overhangsthe turntable, means to move the converting unit to bring the scribernear to or further from the centre of the said disc, a light sourcebeneath such cardiogram disc, and a microscope disposed above suchcardiogram disc to permit viewing of the inscribed traces.

5. An improved electrocardiograph as defined in claim 4 characterised bythe combination therewith of a calibrated grid in the microscope A toallow the amplitude of the deflection of the scriber to be read and toallow the time of the heart cycle to be read, the latter calibrationshaving their time-indicating lines radially arwith a moving partof saidconverting unit and arranged to inscribe a minute trace upon the disc bycutting through the coating, and standardisation means to adjust theamplitude of the deflection of 'the scriber comprising, contactsoperated periodically by the motor, voltage supply means associated withsuch contacts, sensitivity control meansfor the amplifier to allowadjustment of the deflection of the scriber, and 'a switch to place suchstandardisation means into the amplifier circuit.

'7 An improved electrocardiograph comprising: a removable cardiogramdisc of glass having its one side smoked, a turntable to support saiddisc,

'a, spring motor to drive said turntable, electrical means to amplifythe action current of the heart, a magnetic moving-coil unit to whichthe electrical impulses are applied, a scriber coupled to such unit andhaving a diamond point, said scriber being coupled to move with themoving coil ofthe said unit and arranged to inscribe a minute trace uponthe disc by cutting through the coating when the disc is revolved, meansto shift the magnetic moving-coil unit in a direction parallel to themovement of the moving coil of such unit, leads from a patient to allowthe action current of a heart to be introduced to the amplifier, aswitch in such leads to place different -leads in circuit for difierentpositions of the switch, and coupling means between the magnetic unitand the switch to cause synchronous positioning of said switchingmeansand said magnetic unit.

8. An improved electrocardiograph comprising:

a removable cardiogram disc of glass having its underside smoked, ahorizontally-disposed turntable of greater diameter than the said discto support said disc upon its top, a spring motor to drive saidturntable, electrical means to amplify the action current of a heart, amagnetic moving-coil unit to change the electrical impulses from theamplifier to mechanical movement, a

scriber havinga diamond point arranged to inscribe a minute trace uponthe underside of said discby. cutting through the coating when the discis revolved, an arm connecting the scriber with the said moving coil,said arm being disposed parallel to the axis of the moving coil, asecond arm secured at one end to the scriber and tangentially disposed(at the point of contact of the scriber) to the trace being inscribed,and a bracket projecting from the magnet of the said moving coil unitsupporting the projecting end of the last-said arm.

' EDWARD THOMAS BOTH.

